1. Field of the Invention
The present invention relates to an improvement in a signal wire of a hand-free receiver for a mobile telephone.
2. Description of the Related Prior Art
A conventional hand-free receiver 1 is shown in FIG. 1, and can be used for holding a mobile telephone 2 such that the mobile telephone 2 can be used in the car. However, the volume, the signal connecting receptacle and the working voltage of the mobile telephone 2 are variable because it is made by different factories so that it has to provide hand-free receivers of different types so as to suit mobile telephones of various types, thereby increasing the manufacturing cost. A hand-free receiver with a common type of receiving base has been developed, however, it still cannot solve the following problems:
(1) Different types of mobile telephones will need different power supply voltages.
(2) Different types of mobile telephones will need different kinds of signal output plugs.
(3) Different types of mobile telephones will need different voice output powers.
The primary objective of the present invention is to provide a signal wire connecting between a hand-free receiver and a mobile telephone, the signal wire including a first side comprising a hand-free receiver plug co-operating with the hand-free receiver so as to be connected to the main circuit of the hand-free receiver, and a second side comprising a mobile telephone plug co-operating with the output receptacle of the mobile telephone so as to be connected to the mobile telephone.
By such an arrangement, the mobile telephone plug includes a voltage control leg provided with a first branch resistor which is adapted to match the power supply circuit of the hand-free receiver to obtain the exact voltage supply value of the mobile telephone, which can be outputted to the power supply input leg of the mobile telephone to function as the power supply of the mobile telephone. In addition, the mobile telephone plug includes a mobile telephone voice output leg provided with a second branch resistor which is adapted to output the voice from the mobile telephone to the voice signal of the input side of the voice amplifying circuit of the hand-free receiver so as to obtain a determined value of the voice signal such that the voice amplifying circuit of the hand-free receiver operates precisely.
Further objectives and advantages of the present invention will become apparent after a careful reading of the detailed description with appropriate reference to the accompanying drawings.